1. Field of the Invention
The present invention relates to a semiconductor apparatus, and in particular to a resin sealed semiconductor apparatus.
2. Related Arts
For a resin sealed semiconductor apparatus, a semiconductor device having a plurality of electrodes, such as bonding pads, is fixed at a predetermined position in a lead frame having a plurality of inner leads, the electrodes and the corresponding inner leads are connected together by bonding wires, and the inner leads, the semiconductor device and the bonding wires are sealed by using a sealing resin.
Such a conventional semiconductor apparatus is shown in FIGS. 1A and 1B.
As is shown in FIG. 1A, the semiconductor apparatus comprises: a lead frame having a plurality of inner leads 1; a pressure sensitive double coated adhesive tape 2 applied on the lower face of each inner lead 1 of the lead frame; a semiconductor device 3 bonded to the adhesive tape 2 and having a plurality of electrodes; a plurality of bonding wires 4 used to connect the electrodes of the semi-conductor device 3 to the corresponding inner leads 1; and a sealing resin 5 for sealing the semiconductor device 3, which is bonded to the inner leads 1 (the lead frame) by the adhesive tape 2, and the bonding wires 4.
In this semiconductor apparatus, to seal the inner leads 1 using the sealing resin 5, as is shown in FIG. 1B, the lead frame having the inner leads 1 is placed in a sealing jig 7 and the sealing resin 5 is introduced into the sealing jig 7 through a sealing gate 71. At this time, the quantity of the introduced sealing resin 5 tends to vary at the upper face and the lower face of the semiconductor device 3, consistent with the shapes and positions of the inner leads 1 and the semiconductor device 3 and the condition of the sealing resin 5 when it is introduced. Since in this case, particularly, more sealing resin 5 tends to be introduced at the lower face of the semiconductor device 3, it is shifted upward until the bonding wires 4 are exposed at the surface of the sealing resin 5.
To resolve this problem, Japanese Unexamined Patent Publication No. Hei 5-47979 proposes that a support lead is provided for the lead frame to prevent the shifting of the semiconductor device.
Another example of a semiconductor apparatus having a support lead is shown in FIG. 2.
In this semiconductor apparatus, a semiconductor 3 is mounted and fixed to an island 81 comprising a lead frame, and support leads 9a and 9b, coated with an insulating tape, are provided at predetermined positions (the island 81, etc.) in the lead frames so that the island 81 and the semiconductor device 3 will not be shifted when they are sealed by a sealing resin 5.
Since the constant distance between the island 81 and the internal wall of a sealing jig is maintained by the support leads 9a and 9b when the semiconductor device is sealed by the sealing resin 5, the island 81 is not shifted, and thus the bonding wires 4 are prevented from being exposed at the surface of the sealing resin 5.
In the first conventional semiconductor apparatus as above-mentioned, when the semiconductor device is sealed with the sealing resin 5, it is shifted upward and the bonding wires 4 are exposed at the surface to the sealing resin 5, resulting in deterioration of performance and reliability. In the second conventional semiconductor apparatus, although the island 81 and the semiconductor device 3 are prevented from shifting by the support leads 9a and 9b, since the support leads 9a and 9b are exposed at the surface of the sealing resin 5, moisture easily enters from the exterior along the support leads 9a and 9b, resulting in deterioration in resistance to moisture and also, as in the first example, degradation of performance and reliability.